scrape pool doesn't rely on context as Stop() needs to be blocking to prevent Scrape loops trying to write to a closed TSDB storage.

cmd/prometheus/main.go

@@ -231,16 +231,24 @@ func main() {
 
 	cfg.queryEngine.Logger = log.With(logger, "component", "query engine")
 	var (
-		notifier                      = notifier.New(&cfg.notifier, log.With(logger, "component", "notifier"))
+		ctxWeb, cancelWeb             = context.WithCancel(context.Background())
 		ctxDiscovery, cancelDiscovery = context.WithCancel(context.Background())
+		ctxRule                       = context.Background()
+
+		notifier         = notifier.New(&cfg.notifier, log.With(logger, "component", "notifier"))
 		discoveryManager = discovery.NewDiscoveryManager(ctxDiscovery, log.With(logger, "component", "discovery manager"))
-		ctxScrape, cancelScrape       = context.WithCancel(context.Background())
-		scrapeManager                 = retrieval.NewScrapeManager(ctxScrape, log.With(logger, "component", "scrape manager"), fanoutStorage)
+		scrapeManager    = retrieval.NewScrapeManager(log.With(logger, "component", "scrape manager"), fanoutStorage)
 		queryEngine      = promql.NewEngine(fanoutStorage, &cfg.queryEngine)
-		ctxWeb, cancelWeb             = context.WithCancel(context.Background())
-		webHandler                    = web.New(log.With(logger, "component", "web"), &cfg.web)
+		ruleManager      = rules.NewManager(&rules.ManagerOptions{Appendable: fanoutStorage,
+			Notifier:    notifier,
+			QueryEngine: queryEngine,
+			Context:     ctxRule,
+			ExternalURL: cfg.web.ExternalURL,
+			Logger:      log.With(logger, "component", "rule manager"),
+		})
 	)
 
+<<<<<<< HEAD
 	ctx := context.Background()
 	ruleManager := rules.NewManager(&rules.ManagerOptions{
 		Appendable:  fanoutStorage,
@@ -253,6 +261,9 @@ func main() {
 	})
 
 	cfg.web.Context = ctx
+=======
+	cfg.web.Context = ctxWeb
+>>>>>>> 95b1dec3... scrape pool doesn't rely on context as Stop() needs to be blocking to prevent Scrape loops trying to write to a closed TSDB storage.
 	cfg.web.TSDB = localStorage.Get
 	cfg.web.Storage = fanoutStorage
 	cfg.web.QueryEngine = queryEngine
@@ -274,6 +285,9 @@ func main() {
 		cfg.web.Flags[f.Name] = f.Value.String()
 	}
 
+	// Depend on cfg.web.ScrapeManager so needs to be after cfg.web.ScrapeManager = scrapeManager
+	webHandler := web.New(log.With(logger, "component", "web"), &cfg.web)
+
 	// Monitor outgoing connections on default transport with conntrack.
 	http.DefaultTransport.(*http.Transport).DialContext = conntrack.NewDialContextFunc(
 		conntrack.DialWithTracing(),
@@ -310,17 +324,6 @@ func main() {
 
 	var g group.Group
 	{
-		g.Add(
-			func() error {
-				err := discoveryManager.Run()
-				level.Info(logger).Log("msg", "Discovery manager stopped")
-				return err
-			},
-			func(err error) {
-				level.Info(logger).Log("msg", "Stopping discovery manager...")
-				cancelDiscovery()
-			},
-		)
 		term := make(chan os.Signal)
 		signal.Notify(term, os.Interrupt, syscall.SIGTERM)
 		cancel := make(chan struct{})
@@ -341,6 +344,34 @@ func main() {
 			},
 		)
 	}
+	{
+		g.Add(
+			func() error {
+				err := discoveryManager.Run()
+				level.Info(logger).Log("msg", "Discovery manager stopped")
+				return err
+			},
+			func(err error) {
+				level.Info(logger).Log("msg", "Stopping discovery manager...")
+				cancelDiscovery()
+			},
+		)
+	}
+	{
+		g.Add(
+			func() error {
+				err := scrapeManager.Run(discoveryManager.SyncCh())
+				level.Info(logger).Log("msg", "Scrape manager stopped")
+				return err
+			},
+			func(err error) {
+				// Scrape manager needs to be stopped before closing the local TSDB
+				// so that it doesn't try to write samples to a closed storage.
+				level.Info(logger).Log("msg", "Stopping scrape manager...")
+				scrapeManager.Stop()
+			},
+		)
+	}
 	{
 		// Make sure that sighup handler is registered with a redirect to the channel before the potentially
 		// long and synchronous tsdb init.
@@ -482,19 +513,6 @@ func main() {
 			},
 		)
 	}
-	{
-		g.Add(
-			func() error {
-				err := scrapeManager.Run(discoveryManager.SyncCh())
-				level.Info(logger).Log("msg", "Scrape manager stopped")
-				return err
-			},
-			func(err error) {
-				level.Info(logger).Log("msg", "Stopping scrape manager...")
-				cancelScrape()
-			},
-		)
-	}
 	if err := g.Run(); err != nil {
 		level.Error(logger).Log("err", err)
 	}

discovery/manager.go

@@ -87,7 +87,6 @@ func (m *DiscoveryManager) Run() error {
 			return m.ctx.Err()
 		}
 	}
-
 }
 
 // SyncCh returns a read only channel used by all DiscoveryProviders targetSet updates

retrieval/manager.go

@@ -14,7 +14,6 @@
 package retrieval
 
 import (
-	"context"
 	"fmt"
 
 	"github.com/go-kit/kit/log"
@@ -30,27 +29,27 @@ type Appendable interface {
 }
 
 // NewScrapeManager is the ScrapeManager constructor
-func NewScrapeManager(ctx context.Context, logger log.Logger, app Appendable) *ScrapeManager {
+func NewScrapeManager(logger log.Logger, app Appendable) *ScrapeManager {
 
 	return &ScrapeManager{
-		ctx:           ctx,
 		append:        app,
 		logger:        logger,
 		actionCh:      make(chan func()),
 		scrapeConfigs: make(map[string]*config.ScrapeConfig),
 		scrapePools:   make(map[string]*scrapePool),
+		graceShut:     make(chan struct{}),
 	}
 }
 
 // ScrapeManager maintains a set of scrape pools and manages start/stop cicles
 // when receiving new target groups form the discovery manager.
 type ScrapeManager struct {
-	ctx           context.Context
 	logger        log.Logger
 	append        Appendable
 	scrapeConfigs map[string]*config.ScrapeConfig
 	scrapePools   map[string]*scrapePool
 	actionCh      chan func()
+	graceShut     chan struct{}
 }
 
 // Run starts background processing to handle target updates and reload the scraping loops.
@@ -63,10 +62,18 @@ func (m *ScrapeManager) Run(tsets <-chan map[string][]*config.TargetGroup) error
 			f()
 		case ts := <-tsets:
 			m.reload(ts)
-		case <-m.ctx.Done():
-			return m.ctx.Err()
+		case <-m.graceShut:
+			return nil
+		}
 	}
+}
+
+// Stop cancels all running scrape pools and blocks until all have exited.
+func (m *ScrapeManager) Stop() {
+	for _, sp := range m.scrapePools {
+		sp.stop()
 	}
+	close(m.graceShut)
 }
 
 // ApplyConfig resets the manager's target providers and job configurations as defined by the new cfg.
@@ -123,10 +130,10 @@ func (m *ScrapeManager) reload(t map[string][]*config.TargetGroup) error {
 			return fmt.Errorf("target set '%v' doesn't have valid config", tsetName)
 		}
 
-		// scrape pool doesn't exist so start a new one
+		// Scrape pool doesn't exist so start a new one.
 		existing, ok := m.scrapePools[tsetName]
 		if !ok {
-			sp := newScrapePool(m.ctx, scrapeConfig, m.append, log.With(m.logger, "scrape_pool", tsetName))
+			sp := newScrapePool(scrapeConfig, m.append, log.With(m.logger, "scrape_pool", tsetName))
 			m.scrapePools[tsetName] = sp
 			sp.Sync(tgroup)
 
@@ -134,7 +141,7 @@ func (m *ScrapeManager) reload(t map[string][]*config.TargetGroup) error {
 			existing.Sync(tgroup)
 		}
 
-		// cleanup - check config and cancel the scrape loops if it don't exist in the scrape config
+		// Cleanup - check the config and cancel the scrape loops if it don't exist in the scrape config.
 		jobs := make(map[string]struct{})
 
 		for k := range m.scrapeConfigs {

retrieval/scrape.go

@@ -117,7 +117,6 @@ func init() {
 type scrapePool struct {
 	appendable Appendable
 	logger     log.Logger
-	ctx        context.Context
 
 	mtx    sync.RWMutex
 	config *config.ScrapeConfig
@@ -136,7 +135,7 @@ const maxAheadTime = 10 * time.Minute
 
 type labelsMutator func(labels.Labels) labels.Labels
 
-func newScrapePool(ctx context.Context, cfg *config.ScrapeConfig, app Appendable, logger log.Logger) *scrapePool {
+func newScrapePool(cfg *config.ScrapeConfig, app Appendable, logger log.Logger) *scrapePool {
 	if logger == nil {
 		logger = log.NewNopLogger()
 	}
@@ -152,14 +151,15 @@ func newScrapePool(ctx context.Context, cfg *config.ScrapeConfig, app Appendable
 	sp := &scrapePool{
 		appendable: app,
 		config:     cfg,
-		ctx:        ctx,
 		client:     client,
 		targets:    map[uint64]*Target{},
 		loops:      map[uint64]loop{},
 		logger:     logger,
 	}
 	sp.newLoop = func(t *Target, s scraper) loop {
-		return newScrapeLoop(sp.ctx, s,
+		return newScrapeLoop(
+			context.Background(),
+			s,
 			log.With(logger, "target", t),
 			buffers,
 			func(l labels.Labels) labels.Labels { return sp.mutateSampleLabels(l, t) },
@@ -189,7 +189,6 @@ func (sp *scrapePool) stop() {
 		delete(sp.loops, fp)
 		delete(sp.targets, fp)
 	}
-
 	wg.Wait()
 }
 
@@ -582,8 +581,7 @@ func (c *scrapeCache) forEachStale(f func(labels.Labels) bool) {
 	}
 }
 
-func newScrapeLoop(
-	ctx context.Context,
+func newScrapeLoop(ctx context.Context,
 	sc scraper,
 	l log.Logger,
 	buffers *pool.BytesPool,
@@ -605,8 +603,8 @@ func newScrapeLoop(
 		sampleMutator:       sampleMutator,
 		reportSampleMutator: reportSampleMutator,
 		stopped:             make(chan struct{}),
-		ctx:                 ctx,
 		l:                   l,
+		ctx:                 ctx,
 	}
 	sl.scrapeCtx, sl.cancel = context.WithCancel(ctx)
 

retrieval/scrape_test.go

@@ -44,7 +44,7 @@ func TestNewScrapePool(t *testing.T) {
 	var (
 		app = &nopAppendable{}
 		cfg = &config.ScrapeConfig{}
-		sp  = newScrapePool(context.Background(), cfg, app, nil)
+		sp  = newScrapePool(cfg, app, nil)
 	)
 
 	if a, ok := sp.appendable.(*nopAppendable); !ok || a != app {
@@ -231,7 +231,7 @@ func TestScrapePoolReload(t *testing.T) {
 func TestScrapePoolAppender(t *testing.T) {
 	cfg := &config.ScrapeConfig{}
 	app := &nopAppendable{}
-	sp := newScrapePool(context.Background(), cfg, app, nil)
+	sp := newScrapePool(cfg, app, nil)
 
 	wrapped := sp.appender()